ASAS-SN Discovery of Two Probable Bright Supernovae

ATel #7518; J. Brimacombe (Coral Towers Observatory), B. Nicholls (Mt. Vernon Obs., New Zealand), Subo Dong (KIAA-PKU), K. Z. Stanek, T. W.-S. Holoien, C. S. Kochanek, A. B. Danilet, G. Simonian, U. Basu, N. Goss, J. F. Beacom, T. A. Thompson (Ohio State), B. J. Shappee (Hubble Fellow, Carnegie Observatories), J. L. Prieto (Diego Portales; MAS), D. Bersier (LJMU), P. R. Wozniak (LANL), E. Falco (CfA), D. Szczygiel, G. Pojmanski (Warsaw University Observatory),J. M. Fernandez (Observatory Inmaculada del Molino), S. Kiyota (Variable Star Observers League in Japan), R. A. Koff (Antelope Hills Observatory)
on 17 May 2015; 00:08 UT
Distributed as an Instant Email Notice Supernovae
Credential Certification: Krzysztof Stanek (stanek.32@osu.edu)

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During the ongoing All Sky Automated Survey for SuperNovae (ASAS-SN or "Assassin"), using data from the double 14-cm "Cassius" telescope in Cerro Tololo, Chile, we discovered two new, bright transient sources, possibly supernovae, ASASSN-15jf in the galaxy GALEXASC J222510.84-502347.7 and ASASSN-15jg in the galaxy SDSS J104655.44-021927.0:

Object      RA (J2000)     DEC (J2000)       Disc. UT Date   Disc. V mag 
ASASSN-15jf  22:25:11.076 -50:23:47.54     2015-05-12.40    16.5 
ASASSN-15jg  10:46:55.64  -02:19:29.92     2015-05-15.15    16.9

ASASSN-15jf was discovered in images obtained on UT 2015-05-12.40 at V~16.5, and it was also detected on UT 2015-05-09.34 at V~16.5 and on UT 2015-05-15.32 at V~16.7. We do not detect (V>16.6) this object in images taken on UT 2015-05-05.34 and before. An image obtained by LCOGT 1.0m A in Dome C at Sutherland on UT 2015-05-16.16 confirms the discovery of the transient. This figure shows the archival DSS image of the host (left) and the LCOGT V-band confirmation image (right). The red circle has a radius of 5.0" and is centered on the position of the transient in the LCOGT image.

The position of ASASSN-15jf is approximately 1.6" from the center of a galaxy GALEXASC J222510.84-502347.7 (no known redshift via NED).

ASASSN-15jg was discovered in images obtained on UT 2015-05-15.13 at V~16.9. and it was also detected on UT 2015-05-12.05 at V~17.1 and on UT 2015-05-08.04 at V~17.5. We do not detect (V>16.3) this object in images taken on UT 2015-05-06.16 and before. An image obtained by J. Brimacombe on UT 2015-05-16.34 with the RCOS 51-cm telescope in New Mexico confirms the discovery of the transient. This figure shows the archival SDSS g-band image of the host (left) and J. Brimacombe's confirmation image (right). The red circle has a radius of 5.0" and is centered on the position of the transient in J. Brimacombe's image.

The position of ASASSN-15jg is approximately 4" from the center of a galaxy SDSS J104655.44-021927.0 (z=0.036, d~153 Mpc, via NED). If this is indeed a supernova associated with SDSS J104655.44-021927.0, it would have an absolute V-band magnitude of approximately -19.1 (m-M=35.9, A_V=0.12). Follow-up observations, especially spectroscopy, are encouraged.

We thank LCOGT and its staff for their continued support of ASAS-SN. ASAS-SN is supported in part by Mt. Cuba Astronomical Foundation. For more information about the ASAS-SN project, see the ASAS-SN Homepage and the list of all ASAS-SN transients.